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Re: Requirements Document

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Thu, 14 Feb 2002 13:23:11 -0500
Message-ID: <3C6C008F.7DE42D36@cse.lehigh.edu>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: www-webont-wg@w3.org
Peter,

Thank you for your thorough review of the requirements document. I
appologize for not responding sooner, but better late than never, right?

Many of your suggested changes are obvious improvements (e.g., the
wording changes) and will be made without further discussion. However,
you also suggest some very specific substantive changes that I would
like to respond to. In each case I'll recommend a course of action. If
you (or any other group member) takes issue with that action, then
please start a thread concerning it, so that the pros and cons may be
discussed. (I'd like to give major discussion issues their own threads,
so that people can follow the issues they find most important more
easily). Please prefix the subject of all such threads with "REQDOC:"

1) You say that it pegged your "hype-meter." Maybe we did go a little
overboard with the hype, but my understanding was that one of the
reasons for this document is to let people know why they should be
interested in WebOnt. You can't draw attention to yourself without a
little hype.

ACTION: The editor's will tone down the hype a little bit, and be
careful not to overstate what we hope WebOnt will be able to do.

2) You had a problem with the "Ontologies as resources" requirements. I
know you and Dan have had discussions on this. I am unclear if he swayed
your opinion. If not please start a thread describing your specific
objections to this requirement.

ACTION: The requirement will remain unchanged (until further
discussion).

3) You had a problem with the "Referencing with URIs" requirement. In
subsequent discussion with Dan, it appears that you would be happy if we
change the wording to "URIs + fragement ids."

ACTION: Wording for the requirement will mention "fragement ids."

4) You believe the "Properties for statements" requirement (sometimes
called tagging) is too strong. This was a requirement that a number of
participants have expressed good reasons for. If you believe it should
be demoted to an objective, then please start a thread justifying this
belief.

ACTION: The requirement will remain unchanged (until further
discussion).

5) You believe the "Ability to state closed worlds" requirement is too
strong. Once again, this was a requirement that a significant number of
people think is essential. Obviously, we can't make a closed-world
assumption, but the ability to infer negative information from the
absence of positive information is useful. However, I understand your
concern in that this is not a feature found in existing langauges and
may be difficult to implement.

ACTION: We will demote "Ability to state closed worlds" to an objective.
If anyone wishes to argue for it remaining a requirement, please do so.

6) You take issue with "At a minimum, the language should recommend to
users how they can specify their own default mechanisms." If I recall
correctly, this was a resolution made by the group at a recent telecon
after considerable debate on defaults.

ACTION: The requirement will remain unchanged.

7) You believe "speech act support" and "pre- and post- conditions"
should not be objectives. These requirements were originally identified
by the web services group, however there seemed to be minimal support
for them. 

ACTION: We will remove these objectives from the document, unless one
their proponents argues convincingly for them. Once again, the proponent
should start a specific thread on the topic (preferably different
threads for each objective).

If I missed an important issue, you wanted addressed, please let me
know. I look forward to fruitful discussions on these topics.

Jeff




"Peter F. Patel-Schneider" wrote:
> 
> Hi:
> 
> I have a bunch of comments on the Web Ontology Requirements document (Feb 7).
> 
> There are a lot of places where the wording needs to be changed.  I
> have carefully gone over the first section and have noted the worst
> problems in other sections, but there are lots more places where the
> wording is not correct.
> 
> The document suffers from a serious case of self-importance.  In
> particular,
> 
>         The Web Ontology language will be a significant advance in Web
>         functionality and take interoperability beyond the present stage.
> 
> pegged my hype-meter.  I think that we should be very careful to not make
> such statements, particularly in a requirements document.
> 
> The document still reads as if it was the separate creation of
> different people.  The style should be at least a bit more uniform between
> the various use cases subsections.
> 
> The order of the design goals is rather strange.  In particular, I
> would think that it would be better to move 3.4 before 3.3
> 
> The document uses words with technical meaning in places where the
> technical meaning may not be what is wanted.  In particular,  unless
> ``resource'' means what it means in RDF I think that it should be avoided.
> So
>         Ontologies must be resources with their own unique identifiers.
> can easily be read as implying that ontologies must be objects just like
> regular objects.
> 
> The document anticipates some technical features of OWL.  In particular, it
> uses URI as the term identification mechanism.  This brings up the URI vs
> QName discussion.
> 
> There are a number of places where the document places very strong
> requirements on OWL.  In particular it states
>         The language *must* allow properties to be associated with
>         statements.
> I don't see this requirement on our ``A'' list.
> There are other very strong requirements in the document, including the
> closed-world requirement.  This placing of requirements on OWL continues
> even into the Objectives section, where it says
>         At a minimum, the language should recommend to users how they can
>         specify their own default mechanisms.
> 
> The beginning of Section 5 goes even further, and calls the requirements in
> Section 4 ``minimal [...] features''.  This seems to be setting the WG up
> to fail big-time if even one of the requirements in Section 4 is not
> totally solved by OWL.
> 
> The lexical representations requirement seems to be arguing that URIs have
> to have multiple lexical forms.  I don't think that this is what was wanted
> here.
> 
> Many of the requirements and objectives are not very well specified.  In
> particular, what does it mean to
>         support the use of variables in ontology definitions.
> 
> Some of the objectives go beyond a web ontology language.  For example,
> I view speech acts and conditions outside of a web ontology language if
> there is any semantics attached to their constructs.
> 
> Here are some specific wording changes:
> 
> It shall provide ...
>         The language shall provide ...
> 
> for such a language.
>         to support these g & r.
>         [use cases are not really *for* a language]
> 
> i.e. the objectives
>         i.e., the objectives
> 
> and which tasks support it.
>         and which tasks require it.
>         [tasks don't support design goals---maybe you could change to
>         support the inclusion of]
> 
> of standard vocabularly terms
>         of standard terms
>         [it might be better to keep away from anything with a natural
>         language tone to it]
> 
> This notion of ontologies comes from Artificial Intelligence,
>         [I don't think that this is really true, and in any case, I don't
>         what to ghettoize this view of ontologies]
> 
> terms in an ontology are not just defined in some natural language,
> they also have logical definitions
>         [Again, I would stay away from NL.  Also, the terms in a WebOnt
>         ontology won't be defined in NL.]
> 
> and attributes defined by DTDs or XML Schemas do not have any semantics
> associated with them;
>         [This is a very strong statement.  It might be fine for an opinion
>         piece, but do we really want to get all the XML people even madder
>         with us?]
> 
> In RDF Schema, you can
>         RDF Schema can
>         [I would stay away from the use of second-person.]
> 
> and you can define properties
>         and can define properties
> 
> richer semantics are needed.
>         [statements like this need some justification]
> 
> One of the goals of this document is to specify exactly what is
> needed by a Web Ontology language
>         [I thought that this was an initial list, not the final one.]
> 
> There are numerous uses for ontologies on the Web.
>         [This should, if included, be in the first section.]
> 
> be the
>         be that
> 
> large corporations massive
>         large corporation's
>         [is massive really needed here]
> 
> Language neutral representation
>         Language-neutral representation
> 
> changing any axioms, thus determining backwards-compatibility requires
> more than a simple comparison of axioms.
>         [This assumes that an ontology will contain axioms.]
> 
> low-learning barrier
>         low learning barrier
> 
> an reused
>         and reused
Received on Thursday, 14 February 2002 13:23:14 GMT

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